Baby daddy? My fertile days were from January 28th to February 2nd

I had sex with my boyfriend on Jan 31st he did come inside while I was on top, then I had sex with guy#2 on Feb 2nd he did not come inside he used the pull out. My last period was Jan 17. I'm pregnant now. Who is the father of my baby, my cycle is usually 28 days and last for 5 days. My menstrual calendar says i was apperantly ovulating on Jan 28th and my last fertile day was Feb 2nd.please help :/